The invention relates generally to the field of welding systems, and more particularly to welding wires that improve characteristics of a weld.
Welding systems generally make use of electrodes configured to pass an arc between a torch and a workpiece, thereby heating the workpiece to create a weld. A number of forms of welding are known and are generally used in the art. In many systems, such as metal inert gas (MIG) systems, the wire electrode is advanced through a welding torch and is generally consumed by the heat of the arc. In such operations, the wire electrode may also be referred to as a “filler material” that becomes part of the weld. Although gas is used to shield the weld in many applications, certain types of welding wire do not require shielding gas, and with such wires it would be unusual or even not recommended to use a gas. These may be referred to as self-shielded welding wires.
The selection of the type of wire electrode used for a particular welding application may be based on several factors, including, the composition of the metals being welded, the joint design and the material surface conditions. In general, it is desirable that the wire electrode has mechanical properties similar to those of the base material and produces no discontinuities, such as porosity. Mechanical properties of the weld may be characterized, for example, by the yield strength and impact strength (i.e., toughness) of the weld joint. Generally it is desirable that the weld exhibit a yield strength greater than the yield strength of the workpiece. The impact toughness may also be considered as an index of the likelihood of failure of the resulting structure. Therefore, it is desired that the wire electrode include properties to provide a weld with the desired yield strength and toughness.
In addition, wire electrodes may be used in various welding processes. For example, certain applications may require welding on a flat surface while other applications may require welding vertically. The metallurgy of the wire electrode, along with other factors, such as the orientation of the metal parts being joined, may dictate the available and optimal welding positions. Wire electrodes that enable welding in multiple positions are often considered to provide an increased level of flexibility because they are suitable for use in a number of welding situations and environments. For example, a wire electrode that can be used vertically and overhead may enable the joining of pipes and construction members in structural construction.
Accordingly, there is a need for a welding wire that provides a weld including the desired strength and toughness, and that permits welding in various weld positions.